Magma and Water on Mars

--- Martian meteorites tell us part of the fascinating story about when volcanoes erupted and water flowed.

Written by G. Jeffrey Taylor
Hawai'i Institute of Geophysics and Planetology
posted December 27, 2005

Announcement from Planetary Science Research Discoveries [PSRD]

New Issue: Magma and Water on Mars ---- Martian meteorites tell us part
of the fascinating story about when volcanoes erupted and water flowed.

Full story and .pdf link at:

http://www.psrd.hawaii.edu/Dec05/Magma-WaterOnMars.html

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PSRD is an educational journal supported by NASA's Cosmochemistry
Program and the Hawaii Space Grant Consortium to share the latest
research on meteorites, planets, and other solar system bodies.

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Happy New Year from Jeff Taylor and Linda Martel at PSRD,
Hawaii Institute of Geophysics and Planetology,
University of Hawaii
psrd@higp.hawaii.edu
voice (808) 956-3899
fax (808) 956-6322

Thanks for that link, Alex. That was fascinating. It never ceases to amaze me what clever isotope geochemists can do with a few samples. Correction, I should say cosmochemists. So, it looks like the core and mantle differentiated very soon after the planet's formation, and water may have been abundant shortly thereafter, with volcanism and continued evidence for water up until relatively recent times. I hope that is a reasonably accurate, albeit very brief summary of the article.

It sure would be nice to circumvent some of the uncertainties of depending on the sampling mechanisms which deliver Martian meterorites to earth, by having sample return missions where we could actually select the rock samples we want to analyse in our labs. I think it will be a long time before we will be able to make such measurements remotely, on the surface of another planet.

At first though, a mini lab for measuring isotope abundance is not infeasible (compared to the potential danger of bringing back on Earth an eventual martian bacteria). What we need is an IEC tube, and compensating the low energy available with a longer integration time. Just a though, I don't know which isotopes are interesting to measure and each element has its own methods of measurement. Just make sure that the sample is into an outcrop and not just a loose stone which could come from a very different place.
In more, the result may be very different in an old platean like Gusev and a more recent lava flow like on Tharsis. This imposes to make several sampling points, but this problem arises either for a sample return and for an in-situ measurement.

I can think of a mission design that would allow in-situ analysis of Martian rocks and soils.

Land one (or more) big, heavy laboratories. Sell them to Congress as unmanned engineering tests of landing systems for later manned spacecraft. Equip these heavy landers with the types of equipment needed for isotopic analysis and dating analysis, and develop automated sample handling/preparation systems.

Then land a fleet of smaller rovers, all of which have some basic analysis abilities but which are primarily sample-collectors. Land them within roving range of the big, heavy lab.

Then start a multiple-rover trek "home," towards the lab, investigating all of the rocks and soils along the way. As each rover arrives at the lab, it delivers its samples, which are then analyzed and results transmitted back to the PIs here on Earth.

If your rovers are still in good shape, send them out again along different paths, or check out pre-identified sampling targets that your initial survey missed.

If you can land your lab and rovers precisely, you can get a great radial sampling pattern around your lab, out to 50 to 100 km from a central location. The lab is also big and heavy enough that it could deply a seismometer and a heat-flow probe at the base location.

Land six to eight of these lab/rover missions across the Martian globe, and you'll have a pretty good idea what's been happening up there, I think...

-the other Doug

Yeah, I'm always amazed when, for example, a group of scientists can infer from a meteorite recovered 43 years ago in Nigeria that Mars has a "low bulk planet U/Pb ratio." [Borg et al., 2005].

Of course, there are some scientists who label such efforts as "voodoo."

One may have noted Emily Lakdawalla's recent blog entry "Catching up on some reading," which discusses a few interesting papers recently published in JGR-Planets. Those without access to this journal may be interested that PDF reprints of two of the papers she mentioned [Dyar et al., 2005; Glotch and Christensen, 2005] are available online.

Yes, a dating service, even before cosmonauts land on Mars, it will foster manned exploration of Mars.




The problem is that, if it happens that someone in the Congress has some scientific knowledge, he will guess that once datations done and samples analyzed, there will be no more need for human exploration.

I must admit that I haven't kept up with whatever advances may have taken place with regard to the isotopic analysis of rocks in recent years, but I think the various techniques often depend in large part on specialized sample preparation, which can be very different, depending on the mineral phase that must be separated from the rock for analysis. It seems it would be dificult to build a robotic device that could be used effectively for a variety of circumstances, without making something that would be too complicated for a space mission. I suppose if one knew which rocks and minerals would be encountered, a device that could do one or two kinds of extraction and analysis might be practical.

I think you are right there, such a device would risk being extremely complicated, and so being at risk of a break down, and extremely expensive.

There are one advantage to having one laboratory in place, and thats it would be able to look at a larger number of samples.
But im inclined towards a sample return, more tests can be made in a laboratory here than any we cna envision to send to Mars.
Of course the sample return mission would need to be supported by a rover that got an arm and the tools to both identify and bring interesting samples back.

And in the end a sample return would also give good press to the space agency, read ESA & NASA, that accomplish the task.



A dating service for what? Lost, abandoned and lonely spacecraft?
(Sorry-sorry-sorry, couldnt resist.)

Well..... Sojourner needs a "mothership" to adopt her....

A spacecraft wouldn't need a dating service if it visited Itokawa's red light district...

(Anyone else read both those threads? )

New Scientist 17 December 2005 (P52) has a brief half-page article relating to Charles Frankel's Worlds on Fire (Cambridge University Press 2005). In it there's an interesting description of the carbonate volcano in Tanzania which keeps getting mentioned in passing here.

It's called Ol Doinyo Lengai and it exudes alkali-rich lava with high proportions of sodium and potassium carbonates, and low in silicon. The temperature of such lava is only about 550 C, and it is *very* runny, as fluid as oil.

The point is made in the article that such runny lava might mimic situations on Venus, though I think it may more closely resemble Io (in terms of landforms).

Bob Shaw

The reason carbonatites are always invoked for Venus is because of the absurdly long sinuous lava channels found there -- the grandmother of them all, Baltis Vallis, is 1,800 kilometers long and nearly the same width along its entire length with not a single tributary. It is really virtually impossible to explain its existence except by invoking a super-runny magma with a melting temperature close enough to the ambient temperature that it basically won't freeze. Even with that it's hard to explain, because there is no obvious volcanic structure at its source and no obvious terminal deposits. When people talk about how it formed they usually just say "woo woo woo carbonatites woo woo woo" and wave their arms a lot and quickly go on to the next topic. I wrote my master's thesis studying the topography along its length, which presumably started out being monotonically downhill but isn't like that anymore. It's really weird. But cool. I can't wait to see what Venus Express makes of it, though I'm not sure it'll have the resolution to see anything. What I really want is a better topographic map.

--Emily

Some astonishing images from Tanzania:

http://www.decadevolcano.net/volcanoes/afr...ngai.htm#photos

Imagine a gibbous Jupiter hanging in those night-time skies - it's Io!

Bob Shaw

Assuming such a sophisticated unmanned mission is feasible, dating and geochemisty is just the start. At most such probes will help identify the best areas for crewed missions.

Jon